1. Field of the Invention
The invention relates to a laser repair structure of liquid crystal display (LCD) device and method thereof, more particularly to a laser repair structure of LCD device and method thereof by extending the original dummy metal patterns of the LCD device.
2. Description of the Prior Art
Display devices have become a common device in daily life. Televisions or computers all have incorporated display devices for displaying images to the user. The conventional cathode-ray tube (CRT) takes up a lot of space. In certain applications, such as notebook computers, CRT simply cannot be used. Hence, a dot matrix flat display product, such as TFT LCD (thin film transistor liquid crystal display), has been successfully promoted.
The TFT LCD is not a self-illuminating display. Liquid crystal is a substance that has the characteristics of both solid and liquid, whereby the arrangement of liquid crystal will be changed subject to the impetus of external electric field. The TFT, corresponding to one pixel, can apply the controlled electric field to liquid crystal for the purpose of switching orientation of liquid crystal.
However, some unexpected particles will be deposited in the TFT under the manufacturing procedures, especially for the fabrication of the TFT. Such particles may result in abnormal short or open circuits, and the pixel corresponding to such defective TFT cannot be switched ON/OFF normally. This phenomenon is considered a defect.
When the defect occurs and only little defective pixels are found, a laser repair method will be executed generally. A cross-sectional view of a partial structure of a TFT LCD and the traditional laser repair method are illustrated in FIG. 1. The TFT LCD has a transparent substrate 100, which is a glass substrate generally. There are some TFTs formed on the transparent substrate 100, and each TFT 102 has a corresponding address. Sealant 106 is put around the edges of the transparent substrate 100 and an opening is left before an injection of liquid crystal. A second substrate with a color filter 104 is attached to the sealant 106, and the liquid crystal layer 108 is injected into the space formed by the second substrate 104, the transparent substrate 100 and the sealant 106 through the opening. At last, the opening is sealed by the sealant again, and then the semi-finished TFT display device is produced accordingly.
Before executing the next procedure, the switching between bright and dark of each pixel will be checked first. When an abnormal short/open circuit occurred at a defective TFT, the laser repair method will be used. Conventionally, a laser source 110 produces a high-energy laser beam 112, focusing on the defective TFT, so as to cut a metal line of the TFT or destroy the TFT.
Since the mechanism of the above laser repair method is to destroy the TFT, the defective pixel corresponding such TFT will become the permanent dark dot. In other words, such pixel cannot display its color (red, blue and green) under the normal condition, and the color of such dot including the defective pixel is obviously abnormal in comparison to other normal display dots. The user will be aware of its presence easily.